Solid-state imaging device with photoelectric conversion section, method of manufacturing the same, and electronic device with photoelectric conversion section

ABSTRACT

A solid-state imaging device including a semiconductor layer including a photoelectric conversion section receiving incident light and generating a signal charge; and a light absorbing section for absorbing transmitted light transmitted by the photoelectric conversion section and having a longer wavelength than light absorbed by the photoelectric conversion section, the transmitted light being included in the incident light, the light absorbing section being disposed on a side of another surface of the semiconductor layer on an opposite side from one surface of the semiconductor layer, the incident light being made incident on the one surface of the semiconductor layer.

RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.13/242,483 filed Sep. 23, 2011, the entirety of which is incorporatedherein by reference to the extent permitted by law. The presentapplication claims the benefit of priority to Japanese PatentApplication No. JP 2010-225088 filed on Oct. 4, 2010 in the Japan PatentOffice, the entirety of which is incorporated by reference herein to theextent permitted by law.

BACKGROUND

The present disclosure relates to a solid-state imaging device, a methodof manufacturing the same, and an electronic device.

Electronic devices such as a digital video camera, a digital stillcamera, and the like include a solid-state imaging device. Thesolid-state imaging device includes for example a CMOS (ComplementaryMetal Oxide Semiconductor) image sensor and a CCD (Charge CoupledDevice) image sensor.

The solid-state imaging device has a plurality of pixels arranged in animaging plane. Each pixel includes a photoelectric conversion section.The photoelectric conversion section is for example a photodiode. Thephotoelectric conversion section receives light made incident via anexternal optical system on a light receiving surface, and subjects thelight to photoelectric conversion. The photoelectric conversion sectionthereby generates a signal charge.

Of solid-state imaging devices, a CMOS image sensor has pixelsconfigured to include not only a photoelectric conversion section butalso a pixel transistor. The pixel transistor is configured to read outa signal charge generated in the photoelectric conversion section andoutput the signal charge to a signal line as an electric signal.

Solid-state imaging devices of a “frontside illumination type” and a“backside illumination type” are known. In the “frontside illuminationtype,” a photoelectric conversion section receives incident light madeincident from the top surface side of a semiconductor substrate on whichtop surface side a pixel transistor, wiring, and the like are provided.Thus, in the case of the “frontside illumination type,” it may bedifficult to improve sensitivity because the wiring and the likedecrease an aperture ratio. On the other hand, in the case of the“backside illumination type,” sensitivity can be improved because aphotoelectric conversion section receives incident light made incidentfrom a bottom surface side on an opposite side from the top surface of asemiconductor substrate on which top surface a pixel transistor, wiring,and the like are provided (see Japanese Patent No. 3759435, forexample).

A solid-state imaging device as described above has an effective pixelregion and an optical black region provided in an imaging plane. Theeffective pixel region has effective pixels arranged therein, in whicheffective pixels a photoelectric conversion section receives incidentlight. The optical black region is provided on a part of the peripheryof the effective pixel region, and has optical black (OB) pixelsarranged therein, which OB pixels are provided with a light shieldinglayer for shielding a photoelectric conversion section from incidentlight. A black level reference signal is output from the OB pixels. Thesolid-state imaging device corrects signals output from the effectivepixels with the signals output from the OB pixels as a reference so asto remove noise components such as a dark current and the like (seeJapanese Patent Laid-Open No. 2005-347708, for example).

SUMMARY

In the “backside illumination type” solid-state imaging device, asemiconductor layer is thinned because the image quality of a picked-upimage may be decreased due to the dependence of sensitivity on an angleof incidence when the semiconductor layer in which a photodiode isprovided is thick. For example, in a case where visible light isreceived, the photodiode is provided in the semiconductor layer having athickness of 5 to 15 μm.

Thus, in the “backside illumination type” solid-state imaging device,the light of a long-wavelength component of incident light made incidentfrom the bottom surface side of the semiconductor layer may betransmitted to the top surface side of the semiconductor layer, andreflected by wiring provided to the top surface of the semiconductorlayer. For example, infrared light having a longer wavelength than thelight of a visible light component may be transmitted and reflected bythe wiring. When the light is reflected by the wiring, the reflectedlight may be mixed in other pixels, and thus color mixture may occur.Thus, there may be a degradation in image quality such as a degradationin the color reproducibility of a picked-up image.

In addition, the mixing of the above-described reflected light in theoptical black (OB) pixels means variations in value of the black levelsignals detected in the OB pixels. Therefore, noise components may notbe removed properly, so that the image quality of a picked-up image maybe degraded.

Thus, it can be difficult to improve the image quality of a picked-upimage in the “backside illumination type” solid-state imaging device.

It is therefore desirable to provide a solid-state imaging device, amethod of manufacturing the same, and an electronic device that canimprove the image quality of a picked-up image and the like.

According to an embodiment of the present technology, there is provideda solid-state imaging device including: a semiconductor layer includinga photoelectric conversion section receiving incident light andgenerating a signal charge; and a light absorbing section for absorbingtransmitted light transmitted by the photoelectric conversion sectionand having a longer wavelength than light absorbed by the photoelectricconversion section, the transmitted light being included in the incidentlight, the light absorbing section being disposed on a side of anothersurface of the semiconductor layer on an opposite side from one surfaceof the semiconductor layer, the incident light being made incident onthe one surface of the semiconductor layer.

According to an embodiment of the present technology, there is provideda solid-state imaging device manufacturing method including: forming asemiconductor layer including a photoelectric conversion sectionreceiving incident light and generating a signal charge; and forming alight absorbing section for absorbing transmitted light transmitted bythe photoelectric conversion section and having a longer wavelength thanlight absorbed by the photoelectric conversion section, the transmittedlight being included in the incident light, the light absorbing sectionbeing disposed on a side of another surface of the semiconductor layeron an opposite side from one surface of the semiconductor layer, theincident light being made incident on the one surface of thesemiconductor layer.

According to an embodiment of the present technology, there is providedan electronic device including: a semiconductor layer including aphotoelectric conversion section receiving incident light and generatinga signal charge; and a light absorbing section for absorbing transmittedlight transmitted by the photoelectric conversion section and having alonger wavelength than light absorbed by the photoelectric conversionsection, the transmitted light being included in the incident light, thelight absorbing section being disposed on a side of another surface ofthe semiconductor layer on an opposite side from one surface of thesemiconductor layer, the incident light being made incident on the onesurface of the semiconductor layer.

In the present technology, a photoelectric conversion section in asemiconductor layer receives incident light and generates a signalcharge. A light absorbing section absorbs transmitted light transmittedby the photoelectric conversion section and having a longer wavelengththan light absorbed by the photoelectric conversion section, thetransmitted light being included in the incident light, on a side ofanother surface of the semiconductor layer on an opposite side from onesurface of the semiconductor layer, the incident light being madeincident on the one surface of the semiconductor layer.

According to the present technology, it is possible to provide asolid-state imaging device, a method of manufacturing the same, and anelectronic device that can improve the image quality of a picked-upimage and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a configuration of a camera in a firstembodiment of the present disclosure;

FIG. 2 is a block diagram showing a general configuration of asolid-state imaging device in the first embodiment of the presentdisclosure;

FIG. 3 is a diagram showing principal parts of the solid-state imagingdevice in the first embodiment of the present disclosure;

FIG. 4 is a diagram showing principal parts of the solid-state imagingdevice in the first embodiment of the present disclosure;

FIG. 5 is a diagram showing principal parts of the solid-state imagingdevice in the first embodiment of the present disclosure;

FIGS. 6A, 6B, and 6C are diagrams showing the operation of thesolid-state imaging device in the first embodiment of the presentdisclosure;

FIGS. 7A to 7F are diagrams of a method of manufacturing the solid-stateimaging device in the first embodiment of the present disclosure;

FIG. 8 is a diagram showing principal parts of a solid-state imagingdevice in a second embodiment of the present disclosure;

FIGS. 9A and 9B are diagrams of a method of manufacturing thesolid-state imaging device in the second embodiment of the presentdisclosure;

FIG. 10 is a diagram showing principal parts of a solid-state imagingdevice in a third embodiment of the present disclosure;

FIGS. 11A and 11B are diagrams of a method of manufacturing thesolid-state imaging device in the third embodiment of the presentdisclosure;

FIG. 12 is a diagram showing principal parts of a solid-state imagingdevice in a fourth embodiment of the present disclosure;

FIGS. 13A, 13B, 13C, and 13D are diagrams showing the operation of thesolid-state imaging device in the fourth embodiment of the presentdisclosure; and

FIG. 14 is a diagram showing principal parts of a solid-state imagingdevice in a fifth embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present disclosure will be described withreference to the drawings.

Incidentally, description will be made in the following order.

1. First Embodiment (Schottky Junction)

2. Second Embodiment (Schottky Junction with Intervening InsulatingFilm)

3. Third Embodiment (PN Junction)

4. Fourth Embodiment (Picking Up Both of Visible Light Image andInfrared Image)

5. Fifth Embodiment (Covering Transfer Gate)

6. Others

1. First Embodiment (1) Device Configuration (1-1) Configuration ofPrincipal Parts of Camera

FIG. 1 is a block diagram showing a configuration of a camera 40 in afirst embodiment of the present disclosure.

As shown in FIG. 1, the camera 40 is an electronic device, and thecamera 40 includes a solid-state imaging device 1, an optical system 42,a control section 43, and a signal processing circuit 44.

The solid-state imaging device 1 receives incident light H made incidentas a subject image via the optical system 42 on an imaging surface PS,subjects the incident light H to photoelectric conversion, and therebygenerates a signal charge. In addition, the solid-state imaging device 1is driven on the basis of a control signal output from the controlsection 43 to read out the signal charge and output the signal charge asraw data.

The optical system 42 includes optical members such as an image forminglens, a diaphragm, and the like. The optical system 42 is arranged so asto condense the light formed by the incident subject image on theimaging surface PS of the solid-state imaging device 1.

The control section 43 outputs various control signals to thesolid-state imaging device 1 and the signal processing circuit 44, andthereby controls and drives the solid-state imaging device 1 and thesignal processing circuit 44.

The signal processing circuit 44 is configured to generate a digitalcolor image of the subject image by subjecting the raw data output fromthe solid-state imaging device 1 to signal processing.

(1-2) Configuration of Principal Parts of Solid-State Imaging Device

A general configuration of the solid-state imaging device 1 will bedescribed.

FIG. 2 is a block diagram showing a general configuration of thesolid-state imaging device 1 in the first embodiment of the presentdisclosure.

The solid-state imaging device 1 according to the present embodiment isa CMOS type image sensor, and includes a semiconductor layer 101, asshown in FIG. 2. This semiconductor layer 101 is for example formed by asemiconductor substrate made of silicon. As shown in FIG. 2, thesemiconductor layer 101 has a pixel region PA and a peripheral regionSA.

As shown in FIG. 2, the pixel region PA is in a rectangular shape, andhas a plurality of pixels P arranged therein in each of a horizontaldirection x and a vertical direction y. That is, the pixels P arearranged in the form of a matrix. The pixel region PA is disposed suchthat the center of the pixel region PA corresponds to the optical axisof the optical system 42.

In the pixel region PA, the pixels P are configured to receive incidentlight H and generate a signal charge. The generated signal charge isread and output by a pixel transistor (not shown). A detailedconfiguration of the pixels P will be described later.

In the present embodiment, the pixel region PA includes an effectivepixel region IMG and an optical black region OPB.

In the effective pixel region IMG of the pixel region PA, the pixels Pare arranged as so-called effective pixels. That is, in the effectivepixel region IMG, the upper parts of the pixels P are opened, and thepixels P receive the incident light H made incident from above, wherebyimaging is performed.

In the pixel region PA, the optical black region OPB is provided on theperiphery of the effective pixel region IMG, as shown in FIG. 2. In thiscase, the optical black region OPB is for example provided in partsbelow and on the left side of the effective pixel region IMG. Theoptical black region OPB has a light shielding film (not shown) providedover the pixels P to prevent the incident light from being made directlyincident on the pixels P.

The pixels P in the optical black region OPB are arranged as so-calledoptical black (OB) pixels. That is, a black level reference signal isoutput from the pixels P in the optical black region OPB. The blacklevel reference signal output from the pixels P is used to performcorrection processing on signals output from the effective pixels so asto remove noise components such as a dark current and the like.

As shown in FIG. 2, the peripheral region SA is situated on theperiphery of the pixel region PA. A peripheral circuit is provided inthe peripheral region SA.

Specifically, as shown in FIG. 2, a vertical driving circuit 13, acolumn circuit 14, a horizontal driving circuit 15, an external outputcircuit 17, a timing generator (TG) 18, and a shutter driving circuit 19are provided as the peripheral circuit.

As shown in FIG. 2, the vertical driving circuit 13 in the peripheralregion SA is provided on the side of the pixel region PA. The verticaldriving circuit 13 is configured to select and drive the pixels P in thepixel region PA in row units.

As shown in FIG. 2, the column circuit 14 in the peripheral region SA isprovided in the vicinity of the lower end part of the pixel region PA.The column circuit 14 performs signal processing on signals output fromthe pixels P in column units. The column circuit 14 in this caseincludes a CDS (Correlated Double Sampling) circuit (not shown), andperforms signal processing to remove fixed pattern noise.

As shown in FIG. 2, the horizontal driving circuit 15 is electricallyconnected to the column circuit 14. The horizontal driving circuit 15includes a shift register, for example. The horizontal driving circuit15 sequentially outputs the signals retained for each column of thepixels P in the column circuit 14 to the external output circuit 17.

As shown in FIG. 2, the external output circuit 17 is electricallyconnected to the column circuit 14. The external output circuit 17performs signal processing on the signals output from the column circuit14, and thereafter outputs the signals to the outside. The externaloutput circuit 17 includes an AGC (Automatic Gain Control) circuit 17 aand an ADC (Analog/Digital Conversion) circuit 17 b. In the externaloutput circuit 17, the AGC circuit 17 a subjects the signals to gaincontrol, and thereafter the ADC circuit 17 b converts the signals fromanalog signals to digital signals and outputs the digital signals to theoutside.

As shown in FIG. 2, the timing generator 18 is electrically connected toeach of the vertical driving circuit 13, the column circuit 14, thehorizontal driving circuit 15, the external output circuit 17, and theshutter driving circuit 19. The timing generator 18 generates varioustiming signals, and outputs the timing signals to the vertical drivingcircuit 13, the column circuit 14, the horizontal driving circuit 15,the external output circuit 17, and the shutter driving circuit 19. Thetiming generator 18 thereby drives and controls each of the parts.

The shutter driving circuit 19 is configured to select the pixels P inrow units and adjust exposure time in the pixels P.

(1-3) Detailed Configuration of Solid-State Imaging Device

Details of the solid-state imaging device according to the presentembodiment will be described.

FIGS. 3 to 5 are diagrams showing principal parts of the solid-stateimaging device in the first embodiment of the present disclosure.

FIG. 3 shows the section of a pixel P provided in the effective pixelregion IMG of the pixel region PA. That is, FIG. 3 shows the section ofa pixel P provided as an effective pixel.

FIG. 4 shows the electric connection relation of each part together withthe section of the pixel P provided as an effective pixel. For theconvenience of description, a wiring layer 111 shown in FIG. 3 is notshown in FIG. 4.

FIG. 5 shows the top surface of the pixel P provided as an effectivepixel. The sections of a part Y1-Y2 and a part X1-X2 shown in FIG. 5 areshown in FIG. 3 and FIG. 4.

Details of the optical black region OPB in the pixel region PA are notshown. However, in contrast to the pixel P in the effective pixel regionIMG shown in FIG. 3 and FIG. 4, a color filter CF and an on-chip lens MLare not provided in the optical black region OPB. A light shielding film(not shown) for shielding pixels P from the incident light H is providedin the optical black region OPB. Each part in the optical black regionOPB is otherwise formed in a similar manner to each part in theeffective pixel region IMG.

As shown in each figure, the solid-state imaging device 1 includes aphotodiode 21, a pixel transistor Tr, and an infrared absorbing section31. The pixel transistor Tr in this case includes a transfer transistor22, an amplifying transistor 23, a selecting transistor 24, and a resettransistor 25, and is configured to read out a signal charge from thephotodiode 21.

In the present embodiment, as shown in FIG. 3 and FIG. 4, thesolid-state imaging device 1 has the pixel transistor Tr such as thetransfer transistor 22 and the like disposed on the top surface side(upper surface side in the figures) of the semiconductor layer 101. Thewiring layer 111 is provided to the top surface side of thesemiconductor layer 101. The photodiode 21 is provided so as to receivethe incident light H made incident from the bottom surface side (lowersurface side in FIG. 3 and FIG. 4) as an opposite side from the topsurface side on a light receiving surface JS.

That is, the solid-state imaging device 1 according to the presentembodiment is a “backside illumination type CMOS image sensor.”

Each part will be described in order.

(a) Photodiode 21

In the solid-state imaging device 1, the photodiode 21 is provided foreach of the plurality of pixels P shown in FIG. 2. That is, photodiodes21 are provided in an imaging plane (xy plane) so as to form lines inthe horizontal direction x and the vertical direction y orthogonal tothe horizontal direction x.

The photodiode 21 is configured to receive the incident light H on thelight receiving surface JS, generate a signal charge by performingphotoelectric conversion, and store the signal charge. The photodiode 21in this case is configured to receive the light of a visible lightcomponent made incident as a subject image in the incident light H andperform photoelectric conversion.

As shown in FIG. 3, the photodiode 21 is for example provided within thesemiconductor layer 101, which is a single crystal siliconsemiconductor. For example, the photodiode 21 is provided in thesemiconductor layer 101 thinned to a thickness of 5 to 15 μm.Specifically, the photodiode 21 includes n-type charge accumulatingregions 101 na and 101 nb. The n-type charge accumulating regions 101 naand 101 nb are provided within p-type semiconductor regions 101 pa and101 pb of the semiconductor layer 101. That is, the p-type semiconductorregion 101 pa and the n-type charge accumulating regions 101 na and 101nb are formed sequentially from the bottom surface side (lower surfacein FIG. 3) to the top surface side (upper surface in FIG. 3) in thesemiconductor layer 101. In addition, the n-type charge accumulatingregions 101 na and 101 nb are formed so as to increase in impurityconcentration from the bottom surface side to the top surface side ofthe semiconductor layer 101.

A p-type semiconductor region 101 pc having a higher impurityconcentration than the p-type semiconductor regions 101 pa and 101 pb isprovided as a hole accumulating layer in the n-type charge accumulatingregions 101 na and 101 nb on the top surface side of the semiconductorlayer 101. That is, the high-concentration p-type semiconductor region101 pc is formed closer to the top surface than the n-type chargeaccumulating regions 101 na and 101 nb in the semiconductor layer 101.

The photodiode 21 is thus formed with a so-called HAD (Hall AccumulatedDiode) structure.

As shown in FIGS. 3 to 5, a signal charge accumulated in each photodiode21 is transferred to a floating diffusion FD by the transfer transistor22.

The photodiodes 21 are provided in both of the effective pixel regionIMG and the optical black region OPB (see FIG. 2) in a similar manner.In addition, a reverse bias is applied to the photodiodes 21.

(b) Pixel Transistor Tr

In the solid-state imaging device 1, the pixel transistor Tr is providedin each of the plurality of pixels P shown in FIG. 2. As shown in eachfigure, the transfer transistor 22, the amplifying transistor 23, theselecting transistor 24, and the reset transistor 25 are provided as thepixel transistor Tr.

Each of the transistors 22 to 25 forming the pixel transistor Tr isprovided on the top surface side of the semiconductor layer 101, asshown in FIG. 3 and FIG. 4. As shown in FIG. 5, each of the transistorsis provided so as to be situated below the photodiode 21 in the imagingplane (xy plane). Each of the transistors 22 to 25 is formed as anN-channel MOS transistor, for example.

For example, an activation region (not shown) is formed in a region forseparation between pixels P in the semiconductor layer 101, andrespective gate electrodes 22G, 23G, 24G, and 25G of the transistors 22to 25 are formed by using polysilicon. Incidentally, though not shown,sidewalls (not shown) are formed on side parts of the respective gateelectrodes 22G, 23G, 24G, and 25G.

These transistors 22 to 25 are provided in both of the effective pixelregion IMG and the optical black region OPB (see FIG. 2) in a similarmanner.

(b-1) Transfer Transistor 22

In the pixel transistor Tr, as shown in FIG. 3, the transfer transistor22 is provided on the top surface side of the semiconductor layer 101.

In this case, as shown in FIG. 3, the gate electrode 22G of the transfertransistor 22 is provided to the top surface of the semiconductor layer101 with a gate insulating film 22 z interposed between the gateelectrode 22G and the semiconductor layer 101.

As shown in FIG. 3, the gate electrode 22G of the transfer transistor 22is provided so as to be adjacent to the floating diffusion FD providedin the top surface of the semiconductor layer 101. The gate electrode22G is provided to a channel formation region of the transfer transistor22 for transferring a signal charge from the photodiode 21 to thefloating diffusion FD with the gate insulating film 22 z interposedbetween the gate electrode 22G and the channel formation region.

As shown in FIG. 4, the transfer transistor 22 is configured to outputthe signal charge generated in the photodiode 21 to the gate of theamplifying transistor 23 as an electric signal.

Specifically, the gate of the transfer transistor 22 is supplied with atransfer signal TG from a transfer line (not shown), and therebytransfers the signal charge accumulated in the photodiode 21 to thefloating diffusion FD. The floating diffusion FD converts the chargeinto a voltage, and inputs the voltage to the gate of the amplifyingtransistor 23 as an electric signal.

(b-2) Amplifying Transistor 23

In the pixel transistor Tr, as shown in FIG. 3, the amplifyingtransistor 23 is provided on the top surface side of the semiconductorlayer 101.

As shown in FIG. 3, the gate electrode 23G of the amplifying transistor23 is provided to the top surface of the semiconductor layer 101 with agate insulating film 23 z interposed between the gate electrode 23G andthe semiconductor layer 101. The amplifying transistor 23 is providedbetween the selecting transistor 24 and the reset transistor 25 providedto the top surface of the semiconductor layer 101.

As shown in FIG. 4, the amplifying transistor 23 is configured toamplify and output an electric signal obtained by the conversion fromthe charge to the voltage in the floating diffusion FD.

Specifically, the gate of the amplifying transistor 23 is electricallyconnected to the floating diffusion FD by wiring. In addition, the drainof the amplifying transistor 23 is electrically connected to a powersupply line (not shown), to which a power supply potential VDD isapplied. In addition, the source of the amplifying transistor 23 iselectrically connected to the drain of the selecting transistor 24. Whenthe selecting transistor 24 is set in an on state by a selecting signalSEL, the amplifying transistor 23 is supplied with a constant current,and operates as a source follower. Thus, the amplifying transistor 23amplifies the electric signal obtained by the conversion from the chargeto the voltage in the floating diffusion FD.

(b-3) Selecting Transistor 24

In the pixel transistor Tr, as shown in FIG. 3, the selecting transistor24 is provided on the top surface side of the semiconductor layer 101.

In this case, as shown in FIG. 3, the gate electrode 24G of theselecting transistor 24 is provided to the top surface of thesemiconductor layer 101 with a gate insulating film 24 z interposedbetween the gate electrode 24G and the semiconductor layer 101. Theselecting transistor 24 is provided so as to be adjacent to theamplifying transistor 23 provided in the top surface of thesemiconductor layer 101.

As shown in FIG. 4, the selecting transistor 24 is configured to outputthe electric signal output from the amplifying transistor 23 to avertical signal line (not shown) when the selecting signal is input tothe selecting transistor 24.

Specifically, the gate of the selecting transistor 24 is electricallyconnected to an address line (not shown) supplied with the selectingsignal SEL. When the selecting transistor 24 is set in an on state bybeing supplied with the selecting signal SEL, the selecting transistor24 outputs the output signal amplified by the amplifying transistor 23as described above to the vertical signal line (not shown).

(b-4) Reset Transistor 25

In the pixel transistor Tr, as shown in FIG. 3, the reset transistor 25is provided on the top surface side of the semiconductor layer 101.

In this case, as shown in FIG. 3, the gate electrode 25G of the resettransistor 25 is provided to the top surface of the semiconductor layer101 with a gate insulating film 25 z interposed between the gateelectrode 25G and the semiconductor layer 101. The reset transistor 25is provided so as to be adjacent to the amplifying transistor 23provided in the top surface of the semiconductor layer 101.

As shown in FIG. 4, the reset transistor 25 is configured to reset thegate potential of the amplifying transistor 23.

Specifically, as shown in FIG. 4, the gate of the reset transistor 25 isconnected to a reset line (not shown) supplied with a reset signal. Inaddition, the drain of the reset transistor 25 is electrically connectedto the power supply line (not shown), so that the power supply potentialVDD is applied to the drain of the reset transistor 25. In addition, thesource of the reset transistor 25 is electrically connected to thefloating diffusion FD. When the gate of the reset transistor 25 issupplied with the reset signal RST from the reset line (not shown) andthereby the reset transistor 25 is set in an on state, the resettransistor 25 resets the gate potential of the amplifying transistor 23to the power supply potential VDD via the floating diffusion FD.

(c) Infrared Absorbing Section 31

In the solid-state imaging device 1, the infrared absorbing section 31is provided in each of the plurality of pixels P shown in FIG. 2.

The infrared absorbing section 31 is configured to absorb infrared lightpassed through the photodiode 21, which infrared light is included inthe incident light H made incident as a subject image. That is, beforethe light of a longer wavelength than that of a visible light componentselectively absorbed by the photodiode 21 is passed through thephotodiode 21 and made incident on the wiring layer 111 on the topsurface side, the light of the longer wavelength and the visible lightcomponent being included in the incident light H made incident from thebottom surface side, the infrared absorbing section 31 selectivelyabsorbs the light of the longer wavelength, and thereby provides a lightshielding.

In the present embodiment, as shown in FIG. 3, the infrared absorbingsection 31 includes a metallic silicide layer 301S. The metallicsilicide layer 301S is provided so as to cover the surface of the p-typesemiconductor region 101 pc in the semiconductor layer 101.

This metallic silicide layer 301S is provided so as to form a Schottkyjunction with the p-type semiconductor region 101 pc in thesemiconductor layer 101. That is, the infrared absorbing section 31 isformed so as to constitute a Schottky diode, with a Schottky barrierformed in a junction part between the metallic silicide layer 301S andthe p-type semiconductor region 101 pc in the semiconductor layer 101.The infrared absorbing section 31 is formed so as to have a band gapabsorbing infrared rays. For example, the infrared absorbing section 31is formed so as to have a band gap of 0.6 eV (corresponding to awavelength of 2 μm) or less.

For example, the metallic silicide layer 301S is formed of Pt (platinum)silicide. In addition to Pt (platinum) silicide, the metallic silicidelayer 301S may be formed of Co silicide, Pd silicide, or Ir silicide. Inaddition, a metallic layer formed of a metal such as Au, Ni, Co, Pd, Ir,W or the like may be provided in place of the metallic silicide layer301S.

In the infrared absorbing section 31, a reverse bias voltage is appliedto the Schottky diode. Specifically, as shown in FIG. 4, the metallicsilicide layer 301S is electrically connected to the power supply line(not shown), so that the power supply potential VDD is applied to themetallic silicide layer 301S. A leakage of carriers into the photodiode21 when a floating node is saturated can be thereby prevented.

In addition, as shown in FIG. 5, the metallic silicide layer 301S isformed so as to cover the photodiode 21 in the imaging plane (xy plane).

The infrared absorbing section 31 is provided in both of the effectivepixel region IMG and the optical black region OPB (see FIG. 2) in asimilar manner.

(d) Others

In addition to the above, as shown in FIG. 3, a color filter CF and anon-chip lens ML are provided so as to correspond to pixels P on thebottom surface side (lower surface side in FIG. 3) of the semiconductorlayer 101 in the effective pixel region IMG of the pixel region PA.

The color filter CF for example includes filter layers of three primarycolors. The filter layers of three primary colors are arranged in therespective pixels P in a Bayer arrangement. The color filter CF is forexample formed by applying a coating liquid including a coloring pigmentand a photoresist resin by a coating method such as a spin coatingmethod or the like, thereby forming a coating film, and thereaftersubjecting the coating film to pattern processing by lithographytechnology.

As shown in FIG. 3, the on-chip lens ML is a convex lens whose center isthicker than an edge thereof, and is configured to condense the incidentlight H onto the light receiving surface JS of the photodiode 21 via thecolor filter CF.

For example, the on-chip lens ML is formed by using a transparentorganic material such as a styrene resin, an acrylic resin, a novolacresin or the like. In addition, the on-chip lens ML may be formed byusing a transparent inorganic material such as SiO₂, SiN, SiON, SiCN,HfO or the like.

In addition, as shown in FIG. 3, the wiring layer 111 is provided to thetop surface of the semiconductor layer 101 so as to cover the pixeltransistor Tr and the infrared absorbing section 31 described above. Inthe wiring layer 111, a plurality of pieces of wiring 111 h electricallyconnected to respective elements are provided between a plurality ofinterlayer insulating films (not shown) forming an insulating layer 111z. That is, the wiring layer 111 is formed by alternately stacking theinterlayer insulating films (not shown) and the pieces of wiring 111 h.Each of the pieces of wiring 111 h is formed in a laminated state so asto function as wiring such as the transfer line, the address line, thevertical signal line, and the reset line electrically connected to thepixel transistor Tr, for example. In addition, a supporting substrate(not shown) is laminated for reinforcement to the surface of the wiringlayer 111 on the opposite side from the surface of the wiring layer 111to which surface the semiconductor layer 101 is provided.

Incidentally, in contrast to the pixels P of the effective pixel regionIMG shown in FIG. 3 and FIG. 4, the color filter CF and the on-chip lensML are not provided in the optical black region OPB of the pixel regionPA. The optical black region OPB is provided with a light shielding film(not shown) for shielding the pixels P from the incident light H.

FIGS. 6A, 6B, and 6C are diagrams showing the operation of thesolid-state imaging device 1 in the first embodiment of the presentdisclosure.

FIGS. 6A, 6B, and 6C are a timing chart showing pulse signals suppliedto the respective parts when a signal is read out from the pixel P. FIG.6A shows the selecting signal SEL input to the gate of the selectingtransistor 24. FIG. 6B shows the transfer signal TG input to the gate ofthe transfer transistor 22. FIG. 6C shows the reset signal RST input tothe gate of the reset transistor 25.

First, as shown in FIGS. 6A to 6C, at a first time point T1, theselecting signal SEL and the reset signal RST at a high level aretransmitted to set the selecting transistor 24 and the reset transistor25 in an on state. The gate potential of the amplifying transistor 23 isthereby reset.

Next, at a second time point T2, the reset signal RST is set to a lowlevel to set the reset transistor 25 in an off state. Thereafter, avoltage corresponding to a reset level is output to the column circuit14 as an output signal.

Next, at a third time point T3, the transfer signal TG at a high levelis transmitted to set the transfer transistor 22 in an on state. Asignal charge accumulated in the photodiode 21 is thereby transferred tothe floating diffusion FD.

Next, at a fourth time point T4, the transfer signal TG is set to a lowlevel to set the transfer transistor 22 in an off state. A voltagehaving a signal level corresponding to the quantity of the transferredsignal charge is thereafter output to the column circuit 14 as an outputsignal.

Next, at a fifth time point T5, the transfer signal TG and the resetsignal RST are set to a high level to set the transfer transistor 22 andthe reset transistor 25 in an on state.

Thereafter, at a sixth time point T6, the selecting signal SEL, thetransfer signal TG, and the reset signal RST are set to a low level toset the selecting transistor 24, the transfer transistor 22, and thereset transistor 25 in an off state.

The column circuit 14 subjects the signal having the reset level readout first and the signal having the signal level read out later todifference processing, and stores a signal resulting from the differenceprocessing. A fixed pattern noise caused by for example variation in Vthof each transistor provided to each pixel P is thereby cancelled out.

Because the gates of the respective transistors 22, 24, and 25 areconnected in a row unit composed of a plurality of pixels P arranged inthe horizontal direction x, the operation of driving the pixel P asdescribed above is performed simultaneously for the plurality of pixelsP arranged in the row unit.

Specifically, the pixels P are selected sequentially in horizontal lines(pixel rows) in the vertical direction by the selecting signal suppliedby the vertical driving circuit 13 described above. Then, thetransistors of each pixel P are controlled by various timing signalsoutput from the timing generator 18. An output signal in each pixel isthereby output to the column circuit 14 in each column of pixels Pthrough the vertical signal line (not shown).

Then, the signal stored in the column circuit 14 is selected by thehorizontal driving circuit 15, and sequentially output to the externaloutput circuit 17.

(2) Manufacturing Method

Principal parts of a manufacturing method for manufacturing thesolid-state imaging device 1 described above will be described.

FIGS. 7A to 7F are diagrams of the method of manufacturing thesolid-state imaging device in the first embodiment of the presentdisclosure.

As with FIG. 3, FIGS. 7A to 7F show a section. The solid-state imagingdevice 1 as shown in FIG. 3 and the like is manufactured by sequentiallyundergoing each step shown in FIGS. 7A to 7F.

(a) Formation of P-Type Semiconductor Regions 101 pa and 101 pb and theLike

First, as shown in FIG. 7A, p-type semiconductor regions 101 pa and 101pb and the like are formed.

In this case, for example, a semiconductor substrate 101B formed of ann-type silicon semiconductor is prepared, and thereafter p-typesemiconductor regions 101 pa and 101 pb and an n-type chargeaccumulating region 101 na are formed in the semiconductor substrate101B.

For example, the regions 101 pa, 101 pb, and 101 na are formed so as tobe in impurity concentration ranges as shown in the following.Specifically, the regions 101 pa, 101 pb, and 101 na are formed by ionimplantation of impurities.

P-Type Semiconductor Regions 101 pa and 101 pb

Impurity Concentration: 1×10¹⁶ to 1×10¹⁸ cm⁻³ (preferably 5×10¹⁶ to5×10¹⁷ cm⁻³)

N-Type Charge Accumulating Region 101 na

Impurity Concentration: 1×10¹⁵ to 1×10¹⁷ cm⁻³ (preferably 5×10¹⁵ to5×10¹⁶ cm⁻³)

Then, an n-type charge accumulating region 101 nb is provided to form aphotodiode 21.

In this case, the n-type charge accumulating region 101 nb is providedin a shallow part on the top surface side in the n-type chargeaccumulating region 101 na.

For example, the n-type charge accumulating region 101 nb is formed byion-implanting an n-type impurity so as to be in an impurityconcentration range as shown in the following.

N-Type Charge Accumulating Region 101 nb

Impurity Concentration: 1×10¹⁶ to 1×10¹⁸ cm⁻³ (preferably 5×10¹⁶ to5×10¹⁷ cm⁻³)

(b) Formation of Insulating Film 20 z and Polysilicon Film 20S

Next, as shown in FIG. 7B, an insulating film 20 z and a polysiliconfilm 20S are formed.

In this case, the insulating film 20 z, which is a silicon oxide film,is formed on the top surface of the semiconductor substrate 101B, andthereafter the polysilicon film 20S is formed. The insulating film 20 zand the polysilicon film 20S are formed so as to cover regions in whichto form the gates of respective transistors 22, 23, 24, and 25 forming apixel transistor Tr.

Specifically, the insulating film 20 z as a silicon oxide film is formedby subjecting the top surface of the semiconductor substrate 101B tothermal oxidation processing. Then, the polysilicon film 20S is formedby a CVD (Chemical Vapor Deposition) method, for example. For example,the polysilicon film 20S is formed so as to include an N-type impurity.

(c) Formation of Pixel Transistor Tr

Next, as shown in FIG. 7C, each of transistors 22, 23, 24, and 25forming a pixel transistor Tr is formed.

In this case, the gate electrodes 22G, 23G, 24G, and 25G of therespective transistors 22, 23, 24, and 25 are formed by subjecting thepolysilicon film 20S (see FIG. 7B) to pattern processing.

Specifically, a resist pattern (not shown) is provided on thepolysilicon film 20S by photolithography technology so as to correspondto a pattern of the gate electrodes 22G, 23G, 24G, and 25G of therespective transistors 22, 23, 24, and 25. Then, the polysilicon film20S is etched with the resist pattern (not shown) as a mask. The gateelectrodes 22G, 23G, 24G, and 25G of the respective transistors 22, 23,24, and 25 are thereby formed from the polysilicon film 20S.

Then, a p-type semiconductor region 101 pc is provided in a shallow parton the top surface side in the n-type charge accumulating region 101 nb.For example, the p-type semiconductor region 101 pc is formed byion-implanting a p-type impurity so as to be in an impurityconcentration range as shown in the following.

P-Type Semiconductor Region 101 pc

Impurity Concentration: 1×10¹⁷ to 1×10¹⁹ cm⁻³ (preferably 5×10¹⁷ to5×10¹⁸ cm⁻³)

Then, the sources and drains of the respective transistors 22, 23, 24,and 25 (including a floating diffusion FD) are formed. For example, thesources and drains of the respective transistors 22, 23, 24, and 25 areformed so as to be in impurity concentration ranges as shown in thefollowing.

Sources and Drains of Respective Transistors 22, 23, 24, and 25

Impurity Concentration: 1×10¹⁹ cm⁻³ or higher Incidentally, though notshown, sidewalls (not shown) are formed on side parts of the respectivegate electrodes 22G, 23G, 24G, and 25G.

(d) Formation of Metallic Layer 301

Next, as shown in FIG. 7D, a metallic layer 301 is formed.

In this case, as shown in FIG. 7D, the metallic layer 301 is formed soas to cover the surface of the p-type semiconductor region 101 pc in thesemiconductor substrate 101B. In addition, the metallic layer 301 isformed so as to cover a part of the gate electrode 22G of the transfertransistor 22 with an insulating film (not shown) interposed between themetallic layer 301 and the part of the gate electrode 22G of thetransfer transistor 22.

Specifically, the insulating film 20 z covering a part on which to formthe metallic layer 301 in the surface of the p-type semiconductor region101 pc of the semiconductor substrate 101B is removed, and the surfaceof that part is exposed. Then, a platinum (Pt) film (not shown) isformed. For example, a platinum (Pt) film having a thickness of 1 nm to50 nm is formed by a sputtering method. Then, the platinum (Pt) film(not shown) is subjected to pattern processing, whereby the metalliclayer 301 is formed.

(e) Formation of Metallic Silicide Layer 301S

Next, as shown in FIG. 7E, a metallic silicide layer 301S is formed.

In this case, as shown in FIG. 7E, the metallic silicide layer 301S isformed by alloying a part of the metallic layer 301 which part faces thep-type semiconductor region 101 pc in the semiconductor substrate 101B.

For example, an annealing process is performed according to thefollowing conditions under a nitrogen atmosphere. Thereby, platinum (Pt)in the metallic layer 301 and silicon (Si) in the p-type semiconductorregion 101 pc are formed into a silicide, and a platinum silicide layeris formed, whereby the metallic silicide layer 301S is provided.

Annealing Process Conditions

-   -   Temperature: 500° C.    -   Process Time: 30 seconds

(f) Removal of Metallic Layer 301

Next, as shown in FIG. 7F, the metallic layer 301 is removed.

In this case, as shown in FIG. 7F, a part other than a part in which themetallic silicide layer 301S is formed in the metallic layer 301 (seeFIG. 7E) is removed, and the surface of the metallic silicide layer 301Sis exposed.

The metallic layer 301 is removed by using aqua regia, for example.

(g) Formation of Other Members such as Wiring Layer 111 and the Like

Next, as shown in FIG. 3, other members such as a wiring layer 111 andthe like are formed.

In this case, the wiring layer 111 is provided to the surface of thesemiconductor substrate 101B above which surface the gate electrodes22G, 23G, 24G, and 25G of the respective transistors 22, 23, 24, and 25are provided. For example, the wiring layer 111 is provided by formingan insulating layer 111 z of an insulating material such as a siliconoxide film or the like and forming wiring 111 h of a metallic materialsuch as aluminum or the like.

Then, after the wiring layer 111 is provided, a supporting substrate(not shown) is laminated to the upper surface of the wiring layer 111.Then, after the semiconductor substrate 101B is inverted, thesemiconductor substrate 101B is subjected to a thinning process. Forexample, a CMP (Chemical Mechanical Polishing) process is performed asthe thinning process. A part of the semiconductor substrate 101B isthereby removed from the bottom surface side.

Specifically, the semiconductor substrate 101B is thinned until thep-type semiconductor region 101 pa is exposed. For example, thesemiconductor substrate 101B is thinned by performing a CMP process sothat the semiconductor substrate 101B has a film thickness of 5 to 15μm, and a semiconductor layer 101 is formed of the semiconductorsubstrate 101B, as shown in FIG. 3.

Then, as shown in FIG. 3, a color filter CF and an on-chip lens ML areprovided on the bottom surface side of the semiconductor layer 101 inthe effective pixel region IMG of the pixel region PA.

On the other hand, in contrast to the pixels P in the effective pixelregion IMG, the color filter CF and the on-chip lens ML are not providedin the optical black region OPB of the pixel region PA. A lightshielding film (not shown) for shielding the light receiving surface JSfrom the incident light H is provided in the optical black region OPB.For example, the light shielding film (not shown) is formed by ametallic material such as aluminum or the like.

Thus, a backside illumination type CMOS image sensor is completed.

(4) Summary

As described above, in the present embodiment, the photodiode 21receiving incident light H and generating a signal charge is provided inthe semiconductor layer 101. This photodiode 21 is formed so as toreceive the light of a visible ray component of the incident light H andgenerate a signal charge. In addition, the pixel transistor Tr foroutputting the signal charge generated in the photodiode 21 as anelectric signal is provided on the side of the top surface on theopposite side from the bottom surface on which the incident light H ismade incident in the semiconductor layer 101. The wiring layer 111including the wiring 111 h connected to the pixel transistor Tr isprovided so as to cover the pixel transistor Tr on the top surface ofthe semiconductor layer 101 (see FIG. 3).

Together with this, the infrared absorbing section 31 is provided on thetop surface side of the semiconductor layer 101 so as to absorbtransmitted light transmitted by the photodiode 21 which transmittedlight has a longer wavelength than light absorbed by the photodiode 21,the transmitted light transmitted by the photodiode 21 and the lightabsorbed by the photodiode 21 being included in the incident light H. Inthis case, the infrared absorbing section 31 is formed so as to absorbinfrared light of the transmitted light transmitted by the photodiode21. This infrared absorbing section 31 is provided so as to beinterposed between the part in which the photodiode 21 is provided inthe semiconductor layer 101 and the wiring layer 111. The infraredabsorbing section 31 includes a Schottky junction, and absorbs infraredlight by the Schottky junction. The Schottky junction of the infraredabsorbing section 31 is formed by joining the metallic silicide layer301S with the p-type semiconductor region 101 pc in the semiconductorlayer 101 (see FIG. 3).

Thus, in the present embodiment, the infrared absorbing section 31absorbs infrared light going toward the wiring layer 111 through thesemiconductor layer 101 before the infrared light is made incident onthe wiring layer 111. That is, the infrared absorbing section 31 blocksthe infrared light. Thus, the present embodiment can prevent theinfrared light from being reflected by the wiring 111 h in the wiringlayer 111, thereby preventing the occurrence of color mixture, andtherefore improve the color reproducibility of a picked-up image.

Together with this, the present embodiment can prevent the mixing ofreflected light reflected by the wiring 111 h in the wiring layer 111 inoptical black (OB) pixels, and thus prevent variation in the value of ablack level signal detected in the OB pixels. Thus, noise components canbe removed properly.

In addition, in the present embodiment, the infrared absorbing section31 absorbs infrared light by the Schottky junction between the metallicsilicide layer 301S and the p-type semiconductor region 101 pc in thesemiconductor layer 101.

Thus, because the Schottky junction is formed by providing the metallicsilicide layer 301S directly on the semiconductor layer 101, the presentembodiment can provide an effect of absorbing infrared rays withoutsubstantial changes in processes or an increase in the number ofprocesses.

Thus, the present embodiment makes it possible to easily improve theimage quality of a picked-up image in the “backside illumination type”solid-state imaging device.

2. Second Embodiment (1) Device Configuration and the Like

FIG. 8 is a diagram showing principal parts of a solid-state imagingdevice in a second embodiment of the present disclosure.

As with FIG. 4, FIG. 8 shows the electric connection relation of eachpart together with the section of a pixel P provided as an effectivepixel. As in FIG. 4, the wiring layer 111 shown in FIG. 3 is not shownin FIG. 8.

As shown in FIG. 8, an infrared absorbing section 31 b in the presentembodiment is different from that of the first embodiment. Except forthis respect and respects related thereto, the present embodiment issimilar to the first embodiment. Thus, repeated description of sameparts will be omitted.

As in the first embodiment, the infrared absorbing section 31 b isconfigured to absorb infrared light passed through a photodiode 21, theinfrared light being included in incident light H made incident as asubject image.

However, in the present embodiment, unlike the first embodiment, theinfrared absorbing section 31 b is provided to the surface of a p-typesemiconductor region 101 pc in a semiconductor layer 101 with aninsulating film 20 z interposed between the infrared absorbing section31 b and the p-type semiconductor region 101 pc, as shown in FIG. 8.That is, the infrared absorbing section 31 b is separated from thesemiconductor layer 101, and the insulating film 20 z is provided so asto be interposed between the infrared absorbing section 31 b and thesemiconductor layer 101.

The infrared absorbing section 31 b includes a polysilicon layer 300 anda metallic silicide layer 301S. The polysilicon layer 300 and themetallic silicide layer 301S are provided so as to be sequentiallylaminated on the insulating film 20 z.

As shown in FIG. 8, the polysilicon layer 300 in the infrared absorbingsection 31 b is formed so as to cover the p-type semiconductor region101 pc in the semiconductor layer 101 with the insulating film 20 zinterposed between the polysilicon layer 300 and the p-typesemiconductor region 101 pc. The polysilicon layer 300 is formed so asto include a p-type impurity.

As shown in FIG. 8, the metallic silicide layer 301S in the infraredabsorbing section 31 b is formed so as to cover the p-type semiconductorregion 101 pc in the semiconductor layer 101 with the insulating film 20z and the polysilicon layer 300 interposed between the metallic silicidelayer 301S and the p-type semiconductor region 101 pc.

The metallic silicide layer 301S is provided so as to form a Schottkyjunction with the polysilicon layer 300. That is, the infrared absorbingsection 31 b is formed so as to constitute a Schottky diode, with aSchottky barrier formed in a junction part between the polysilicon layer300 and the metallic silicide layer 301S. The infrared absorbing section31 b is formed so as to have a band gap absorbing infrared rays. Forexample, the infrared absorbing section 31 b is formed so as to have aband gap of 0.6 eV or less. For example, the metallic silicide layer301S is formed of Pt (platinum) silicide, as in the first embodiment.

In the infrared absorbing section 31 b, a reverse bias voltage isapplied to the Schottky diode, as in the first embodiment. Specifically,as shown in FIG. 8, the polysilicon layer 300 is electrically connectedto a power supply line (not shown), so that a substrate potential VSS isapplied to the polysilicon layer 300. In addition, as shown in FIG. 8,the metallic silicide layer 301S is electrically connected to a powersupply line (not shown), so that a power supply potential VDD differentfrom the substrate potential VSS applied to the polysilicon layer 300 isapplied to the metallic silicide layer 301S.

The infrared absorbing section 31 b is provided in both of an effectivepixel region IMG and an optical black region OPB (see FIG. 2) in asimilar manner.

(2) Manufacturing Method

Principal parts of a manufacturing method for manufacturing thesolid-state imaging device described above will be described.

FIGS. 9A and 9B are diagrams of the method of manufacturing thesolid-state imaging device in the second embodiment of the presentdisclosure.

As with FIG. 8, FIGS. 9A and 9B show a section. The solid-state imagingdevice is manufactured by sequentially undergoing each step shown inFIGS. 9A and 9B.

(a) Formation of Polysilicon Layer 300 and Pixel Transistor Tr

First, as shown in FIG. 9A, a polysilicon layer 300 and a pixeltransistor Tr are formed.

Before this process is performed, the formation of an insulating film 20z and a polysilicon film 20S (see FIG. 7B) is performed in advancetogether with the formation of p-type semiconductor regions 101 pa and101 pb and the like (see FIG. 7A).

Thereafter, the gate electrodes 22G, 23G, 24G, and 25G of respectivetransistors 22, 23, 24, and 25 are formed by subjecting the polysiliconfilm 20S (see FIG. 7B) to pattern processing. Together with this, thepolysilicon layer 300 forming the infrared absorbing section 31 b (seeFIG. 8) is also formed by subjecting the polysilicon film 20S (see FIG.7B) to pattern processing.

Specifically, a resist pattern (not shown) is provided on thepolysilicon film 20S by photolithography technology so as to correspondto a pattern of the gate electrodes 22G, 23G, 24G, and 25G and thepolysilicon layer 300. Then, the polysilicon film 20S is etched with theresist pattern (not shown) used as a mask. The polysilicon layer 300 andthe gate electrodes 22G, 23G, 24G, and 25G of the respective transistors22, 23, 24, and 25 are thereby formed from the polysilicon film 20S.

Then, as in the first embodiment, the sources and drains of therespective transistors 22, 23, 24, and 25 (including a floatingdiffusion FD) are formed.

(b) Formation of Metallic Silicide Layer 301S

Next, as shown in FIG. 9B, a metallic silicide layer 301S is formed.

In this case, a platinum (Pt) film (not shown) is formed on the uppersurface of the polysilicon layer 300. For example, a platinum (Pt) filmhaving a thickness of 1 nm to 50 nm is formed by a sputtering method.Then, a part of the platinum (Pt) film which part faces the polysiliconlayer 300 is alloyed, whereby the metallic silicide layer 301S isformed.

For example, an annealing process is performed according to similarconditions to those of the first embodiment. Thereby, a silicide isformed between the platinum (Pt) layer (not shown) and the polysiliconlayer 300, and a platinum silicide layer is formed, whereby the metallicsilicide layer 301S is provided.

Then, as in the first embodiment, a part other than a part in which themetallic silicide layer 301S is formed in the platinum (Pt) layer (notshown) is removed, and the surface of the metallic silicide layer 301Sis exposed.

Thereafter, as in the first embodiment, other members such as a wiringlayer 111 and the like are formed.

Thus, a backside illumination type CMOS image sensor is completed.

(3) Summary

As described above, in the present embodiment, as in the firstembodiment, the infrared absorbing section 31 b is provided so as toabsorb infrared light of transmitted light transmitted by the photodiode21. The infrared absorbing section 31 b in this case includes thepolysilicon layer 300 provided to the top surface of the semiconductorlayer 101 with the insulating film 20 z interposed between thepolysilicon layer 300 and the top surface of the semiconductor layer101. The Schottky junction of the infrared absorbing section 31 b isformed by joining the polysilicon layer 300 and the metallic silicidelayer 301S with each other.

As in the first embodiment, the infrared absorbing section 31 b absorbsinfrared light going toward the wiring layer 111 through thesemiconductor layer 101 before the infrared light is made incident onthe wiring layer 111. Thus, the present embodiment can prevent theinfrared light from being reflected by the wiring 111 h in the wiringlayer 111, thereby preventing the occurrence of color mixture, andtherefore improve the color reproducibility of a picked-up image.

Together with this, as in the first embodiment, the present embodimentcan prevent the mixing of reflected light reflected by the wiring 111 hin the wiring layer 111 in optical black (OB) pixels, and thus preventvariation in the value of a black level signal detected in the OBpixels. Thus, the present embodiment can remove noise componentsproperly.

In addition, in the present embodiment, the infrared absorbing section31 b is provided to the top surface of the semiconductor layer 101 withthe insulating film 20 z interposed between the infrared absorbingsection 31 b and the top surface of the semiconductor layer 101.

Thus, because the Schottky junction of the infrared absorbing section 31b is not directly provided on the semiconductor layer 101, the presentembodiment can provide an effect of absorbing infrared rays withoutaffecting photodiode characteristics.

Thus, the present embodiment makes it possible to easily improve theimage quality of a picked-up image in the “backside illumination type”solid-state imaging device.

3. Third Embodiment (1) Device Configuration and the Like

FIG. 10 is a diagram showing principal parts of a solid-state imagingdevice in a third embodiment of the present disclosure.

As with FIG. 8, FIG. 10 shows the electric connection relation of eachpart together with the section of a pixel P provided as an effectivepixel. As in FIG. 8, the wiring layer 111 shown in FIG. 3 is not shownin FIG. 10.

As shown in FIG. 10, an infrared absorbing section 31 c in the presentembodiment is different from that of the second embodiment. Except forthis respect and respects related thereto, the present embodiment issimilar to the second embodiment. Thus, repeated description of sameparts will be omitted.

As in the second embodiment, the infrared absorbing section 31 c isconfigured to absorb infrared light passed through a photodiode 21, theinfrared light being included in incident light H made incident as asubject image.

In addition, as in the second embodiment, the infrared absorbing section31 c is provided to the surface of a p-type semiconductor region 101 pcin a semiconductor layer 101 with an insulating film 20 z interposedbetween the infrared absorbing section 31 c and the p-type semiconductorregion 101 pc, as shown in FIG. 10.

However, unlike the second embodiment, the infrared absorbing section 31c includes a P-type section 300Pc and an N-type section 300Nc, and theinfrared absorbing section 31 c is provided on the insulating film 20 zsuch that the P-type section 300Pc and the N-type section 300Nc aresequentially stacked.

The P-type section 300Pc in the infrared absorbing section 31 c isformed by a semiconductor doped with a p-type impurity. As shown in FIG.10, the P-type section 300Pc is formed so as to cover the p-typesemiconductor region 101 pc in the semiconductor layer 101 with theinsulating film 20 z interposed between the P-type section 300Pc and thep-type semiconductor region 101 pc.

The N-type section 300Nc in the infrared absorbing section 31 c isformed by a semiconductor doped with an n-type impurity. As shown inFIG. 10, the N-type section 300Nc is formed so as to cover the p-typesemiconductor region 101 pc in the semiconductor layer 101 with theinsulating film 20 z and the P-type section 300Pc interposed between theN-type section 300Nc and the p-type semiconductor region 101 pc.

The N-type section 300Nc is provided so as to form a pn junction withthe P-type section 300Pc. That is, the infrared absorbing section 31 cis formed so as to constitute a pn junction diode, with a barrier formedin a junction part between the N-type section 300Nc and the P-typesection 300Pc. The infrared absorbing section 31 c is formed so as tohave a band gap absorbing infrared rays. For example, the infraredabsorbing section 31 c is formed so as to have a band gap of 0.6 eV orless.

For example, the P-type section 300Pc is formed by a p-type InGaAscompound semiconductor doped with zinc (Zn), and the N-type section300Nc is formed by an n-type InGaAs compound semiconductor doped withsilicon (Si).

In addition to InGaAs, the P-type section 300Pc and the N-type section300Nc may be formed by a IV or III-V compound semiconductor such as Ge,SiGe, GaAs, InAs, InSb or the like. In addition, the P-type section300Pc and the N-type section 300Nc may be formed by a chalcopyrite typesemiconductor having a narrow band gap.

In the infrared absorbing section 31 c, a reverse bias voltage isapplied to the pn junction diode, as in the second embodiment.Specifically, as shown in FIG. 10, the P-type section 300Pc iselectrically connected to a power supply line (not shown), so that asubstrate potential VSS is applied to the P-type section 300Pc. Inaddition, as shown in FIG. 10, the N-type section 300Nc is electricallyconnected to a power supply line (not shown), so that a power supplypotential VDD different from the substrate potential VSS applied to theP-type section 300Pc is applied to the N-type section 300Nc.

The infrared absorbing section 31 c is provided in both of an effectivepixel region IMG and an optical black region OPB (see FIG. 2) in asimilar manner.

(2) Manufacturing Method

Principal parts of a manufacturing method for manufacturing thesolid-state imaging device described above will be described.

FIGS. 11A and 11B are diagrams of the method of manufacturing thesolid-state imaging device in the third embodiment of the presentdisclosure.

As with FIG. 10, FIGS. 11A and 11B show a section. The solid-stateimaging device is manufactured by sequentially undergoing each stepshown in FIGS. 11A and 11B.

(a) Formation of P-Type Section 300Pc

First, as shown in FIG. 11A, a P-type section 300Pc is formed.

Before this process is performed, the formation of an insulating film 20z and a polysilicon film 20S (see FIG. 7B) is performed in advancetogether with the formation of p-type semiconductor regions 101 pa and101 pb and the like (see FIG. 7A). Further, a pixel transistor Tr isformed (see FIG. 7C).

Thereafter, as shown in FIG. 11A, a P-type section 300Pc is formed.

In this case, as shown in FIG. 11A, the P-type section 300Pc is formedso as to cover the surface of a p-type semiconductor region 101 pc in asemiconductor substrate 101B.

Specifically, a p-type InGaAs compound semiconductor film doped withzinc (Zn) is formed as the

P-type section 300Pc.

(b) Formation of N-Type Section 300Nc

Next, as shown in FIG. 11B, an N-type section 300Nc is formed.

In this case, silicon (Si) is ion-implanted and diffused into a part inwhich to form the N-type section 300Nc in the P-type section 300Pc. TheN-type section 300Nc is thereby formed.

Thereafter, as in the second embodiment, other members such as a wiringlayer 111 and the like are formed.

Thus, a backside illumination type CMOS image sensor is completed.

(3) Summary

As described above, in the present embodiment, as in the otherembodiments, the infrared absorbing section 31 c is provided so as toabsorb infrared light of transmitted light transmitted by the photodiode21. The infrared absorbing section 31 c in this case includes the PNjunction, and absorbs the infrared light by the PN junction.Specifically, the infrared absorbing section 31 c includes the P-typesection 300Pc and the N-type section 300Nc of an opposite conductivitytype to that of the P-type section 300Pc. The P-type section 300Pc isprovided to the top surface of the semiconductor layer 101 with theinsulating film 20 z interposed between the P-type section 300Pc and thetop surface of the semiconductor layer 101. The N-type section 300Nc isprovided to the top surface of the semiconductor layer 101 with theinsulating film 20 z and the P-type section 300Pc interposed between theN-type section 300Nc and the top surface of the semiconductor layer 101.The PN junction of the infrared absorbing section 31 c is formed byjoining the P-type section 300Pc and the N-type section 300Nc with eachother.

As in the other embodiments, the infrared absorbing section 31 c absorbsinfrared light going toward the wiring layer 111 through thesemiconductor layer 101 before the infrared light is made incident onthe wiring layer 111. Thus, the present embodiment can prevent theinfrared light from being reflected by the wiring 111 h in the wiringlayer 111, thereby preventing the occurrence of color mixture, andtherefore improve the color reproducibility of a picked-up image.

Together with this, as in the other embodiments, the present embodimentcan prevent the mixing of reflected light reflected by the wiring 111 hin the wiring layer 111 in optical black (OB) pixels, and thus preventvariation in the value of a black level signal detected in the OBpixels. Thus, the present embodiment can remove noise componentsproperly.

In addition, in the present embodiment, the infrared absorbing section31 c absorbs infrared light by the PN junction. Thus, the presentembodiment can provide a greater effect of absorbing infrared rays byusing a semiconductor material having a higher absorption coefficientfor infrared light than silicon.

Thus, the present embodiment makes it possible to easily improve theimage quality of a picked-up image in the “backside illumination type”solid-state imaging device.

Incidentally, the PN junction of the infrared absorbing section 31 c maybe either of a homojunction and a heterojunction.

4. Fourth Embodiment (1) Device Configuration and the Like

FIG. 12 is a diagram showing principal parts of a solid-state imagingdevice in a fourth embodiment of the present disclosure.

As with FIG. 10, FIG. 12 shows the electric connection relation of eachpart together with the section of a pixel P provided as an effectivepixel. As in FIG. 10, the wiring layer 111 shown in FIG. 3 is not shownin FIG. 12.

As shown in FIG. 12, a transfer transistor 22 d is further provided inthe present embodiment. Except for this respect and respects relatedthereto, the present embodiment is similar to the second embodiment.Thus, repeated description of same parts will be omitted.

As shown in FIG. 12, the transfer transistor 22 d is configured tooutput a signal charge generated in a pn junction diode forming aninfrared absorbing section 31 c to the gate of an amplifying transistor23 as an electric signal.

Specifically, the transfer transistor 22 d has a gate electricallyconnected to a transfer line (not shown) supplied with a transfer signalTG2. The transfer transistor 22 d has a source electrically connected toan N-type section 300Nc of the infrared absorbing section 31 c, and hasa drain electrically connected to a floating diffusion FD and the gateof the amplifying transistor 23. The gate of the transfer transistor 22d is supplied with the transfer signal TG2 from the transfer line (notshown), whereby the transfer transistor 22 d transfers the signal chargeaccumulated in the pn junction diode forming the infrared absorbingsection 31 c to the floating diffusion FD. Then, the floating diffusionFD converts the charge into a voltage, and inputs the voltage as anelectric signal to the gate of the amplifying transistor 23.

Though not shown, the transfer transistor 22 d is provided on the topsurface side of a semiconductor layer 101 as with other transistors 22,23, 24, and 25 as shown in FIG. 3. That is, the gate of the transfertransistor 22 d is provided to the top surface of the semiconductorlayer 101 with a gate insulating film interposed between the gate of thetransfer transistor 22 d and the top surface of the semiconductor layer101.

FIGS. 13A, 13B, 13C, and 13D are diagrams showing the operation of thesolid-state imaging device in the fourth embodiment of the presentdisclosure.

FIGS. 13A, 13B, 13C, and 13D are a timing chart showing pulse signalssupplied to respective parts when a signal is read out from a pixel P.FIG. 13A shows a selecting signal SEL input to the gate of the selectingtransistor 24. FIG. 13B shows a transfer signal TG1 input to the gate ofthe transfer transistor 22. FIG. 13C shows the transfer signal TG2 inputto the gate of the transfer transistor 22 d. FIG. 13D shows a resetsignal RST input to the gate of the reset transistor 25.

First, as shown in FIGS. 13A to 13D, in a period from a first time pointT1 to a time point before a fifth time point T5, a signal having avisible light reset level and a signal having a visible light signallevel are each read out as in the case shown in the first embodimentwith reference to FIGS. 6A to 6C.

Specifically, as shown in FIGS. 13A to 13D, at the first time point T1,the selecting signal SEL and the reset signal RST at a high level aretransmitted to set the selecting transistor 24 and the reset transistor25 in an on state. The gate potential of the amplifying transistor 23 isthereby reset.

Next, at a second time point T2, the reset signal RST is set to a lowlevel to set the reset transistor 25 in an off state. Thereafter, avoltage corresponding to a reset level is output to a column circuit 14as an output signal.

Next, at a third time point T3, the transfer signal TG1 at a high levelis transmitted to set the transfer transistor 22 in an on state. Asignal charge accumulated in a photodiode 21 is thereby transferred tothe floating diffusion FD.

Next, at a fourth time point T4, the transfer signal TG1 is set to a lowlevel to set the transfer transistor 22 in an off state. A voltagehaving a signal level corresponding to the quantity of the transferredsignal charge is thereafter output to the column circuit 14 as an outputsignal.

Thereafter, as shown in FIGS. 13A to 13D, in a period from the fifthtime point T5 to a time point before a ninth time point T9, a signalhaving an infrared light reset level and a signal having an infraredlight signal level are each read out.

In this case, first, as shown in FIGS. 13A to 13D, at the fifth timepoint T5, the selecting signal SEL and the reset signal RST at a highlevel are transmitted to set the selecting transistor 24 and the resettransistor 25 in an on state. The gate potential of the amplifyingtransistor 23 is thereby reset again.

Next, at a sixth time point T6, the reset signal RST is set to a lowlevel to set the reset transistor 25 in an off state. A voltagecorresponding to a reset level is thereafter output as an output signalto the column circuit 14.

Next, at a seventh time point T7, the transfer signal TG2 at a highlevel is transmitted to set the transfer transistor 22 d in an on state.A signal charge accumulated in the pn junction diode forming theinfrared absorbing section 31 c is thereby transferred to the floatingdiffusion FD.

Next, at an eighth time point T8, the transfer signal TG2 is set to alow level to set the transfer transistor 22 d in an off state. A voltagehaving a signal level corresponding to the quantity of the transferredsignal charge is thereafter output to the column circuit 14 as an outputsignal.

Next, at a ninth time point T9, the transfer signals TG1 and TG2 and thereset signal RST are set to a high level to set the transfer transistors22 and 22 d and the reset transistor 25 in an on state.

Thereafter, at a tenth time point T10, the selecting signal SEL, thetransfer signals TG1 and TG2, and the reset signal RST are set to a lowlevel to set the selecting transistor 24, the transfer transistors 22and 22 d, and the reset transistor 25 in an off state.

The column circuit 14 further subjects the signal having the infraredlight reset level read out first and the signal having the infraredlight signal level read out later to difference processing, and stores asignal resulting from the difference processing. A fixed pattern noisecaused by for example variation in Vth of each transistor provided toeach pixel is thereby cancelled out also in the signal relating toinfrared light.

Because the gates of the respective transistors 22, 22 d, 24, and 25 areconnected in a row unit composed of a plurality of pixels P arranged inthe horizontal direction x, the operation of driving the pixel P asdescribed above is performed simultaneously for the plurality of pixelsP arranged in the row unit.

Specifically, as in the other embodiments, the pixels P are selectedsequentially in horizontal lines (pixel rows) in the vertical directionby the selecting signal supplied by a vertical driving circuit 13. Then,the transistors of each pixel P are controlled by various timing signalsoutput from the timing generator 18. An output signal in each pixel isthereby output to the column circuit 14 in each column of pixels Pthrough the vertical signal line (not shown).

Then, the signal stored in the column circuit 14 is selected by ahorizontal driving circuit 15, and sequentially output to an externaloutput circuit 17.

Thereby, as in the other embodiments, a visible light image is generatedfrom the signal relating to visible light. Together with this, unlikethe other embodiments, an infrared light image is generated from thesignal relating to infrared light.

(2) Summary

As described above, in the present embodiment, as in the thirdembodiment, the infrared absorbing section 31 c is provided so as toabsorb infrared light of transmitted light transmitted by the photodiode21.

Therefore, as in the third embodiment, the infrared absorbing section 31c absorbs infrared light going toward the wiring layer 111 through thesemiconductor layer 101 before the infrared light is made incident onthe wiring layer 111. Thus, it is possible to prevent the occurrence ofcolor mixture, and therefore improve the color reproducibility of apicked-up image. Together with this, as in the third embodiment, thepresent embodiment can prevent the mixing of reflected light reflectedby the wiring 111 h in the wiring layer 111 in optical black (OB)pixels. Thus, noise components can be removed properly.

The present embodiment therefore makes it possible to easily improve theimage quality of a picked-up image in the “backside illumination type”solid-state imaging device.

In addition, in the present embodiment, the infrared absorbing section31 c receives infrared light and generates a signal charge. Then, apixel transistor Tr outputs the signal charge generated in the infraredabsorbing section 31 c as an electric signal.

Therefore, the present embodiment generates a visible light image fromthe signal relating to visible light, and is also able to generate aninfrared light image from the signal relating to infrared light, unlikethe other embodiments. That is, both of the visible light image and theinfrared light image can be generated in the same space.

Incidentally, in the present embodiment, imaging is preferably performedwith the solid-state imaging device cooled to minus several ten degreesCelsius by using cooling means such as a Peltier element or the like.This can suppress noise, and improve an S/N ratio.

In addition, imaging may be performed with a subject irradiated withinfrared rays by using an infrared light source (an infrared LED, alaser, or the like).

5. Fifth Embodiment (1) Device Configuration and the Like

FIG. 14 is a diagram showing principal parts of a solid-state imagingdevice in a fifth embodiment of the present disclosure.

As with FIG. 10, FIG. 14 shows the section of a pixel P provided as aneffective pixel. Unlike FIG. 10, the wiring layer 111 shown in FIG. 3 isshown in FIG. 14.

As shown in FIG. 14, an infrared absorbing section 31 e in the presentembodiment is different from that of the third embodiment. Except forthis respect and respects related thereto, the present embodiment issimilar to the third embodiment. Thus, repeated description of sameparts will be omitted.

As in the third embodiment, the infrared absorbing section 31 e isconfigured to absorb infrared light passed through a photodiode 21, theinfrared light being included in incident light H made incident as asubject image. In addition, as in the third embodiment, the infraredabsorbing section 31 e is provided to the surface of a p-typesemiconductor region 101 pc in a semiconductor layer 101 with aninsulating film 20 z interposed between the infrared absorbing section31 e and the p-type semiconductor region 101 pc, as shown in FIG. 14. Inaddition, the infrared absorbing section 31 e is provided such that aP-type section 300Pe and an N-type section 300Ne are sequentiallystacked.

However, unlike the third embodiment, the infrared absorbing section 31e extends over the surface of the semiconductor layer 101 from a partwhere the photodiode 21 is provided, so as to cover the gate electrode22G of a transfer transistor 22. In this case, a part extending so as tocover the gate electrode 22G of the transfer transistor 22 in theinfrared absorbing section 31 e is provided such that an insulatinglayer 111 z forming a wiring layer 111 is interposed between theinfrared absorbing section 31 e and the gate electrode 22G of thetransfer transistor 22.

Specifically, as shown in FIG. 14, the extending part covering the gateelectrode 22G of the transfer transistor 22 in the P-type section 300Pecovers the gate electrode 22G of the transfer transistor 22 with theinsulating layer 111 z interposed between the extending part and thegate electrode 22G of the transfer transistor 22.

In addition, the extending part covering the gate electrode 22G of thetransfer transistor 22 in the N-type section 300Ne covers the gateelectrode 22G of the transfer transistor 22 with the insulating layer111 z and the P-type section 300Pe interposed between the extending partand the gate electrode 22G of the transfer transistor 22.

The P-type section 300Pe in the infrared absorbing section 31 e isformed so as to cover the gate electrode 22G of the transfer transistor22 as well as the surface of the p-type semiconductor region 101 pc in asemiconductor substrate 101B. Thereafter, an n-type impurity ision-implanted and diffused into a part in which to form the N-typesection 300Ne in the P-type section 300Pe. The N-type section 300Ne isthereby formed. As in the third embodiment, the N-type section 300Ne isprovided so as to form a pn junction with the P-type section 300Pe.

In the infrared absorbing section 31 e, a reverse bias voltage isapplied to the pn junction diode, as in the third embodiment.

The infrared absorbing section 31 e is provided in both of an effectivepixel region IMG and an optical black region OPB (see FIG. 2) in asimilar manner.

(2) Summary

As described above, in the present embodiment, as in the thirdembodiment, the infrared absorbing section 31 e is provided so as toabsorb infrared light of transmitted light transmitted by the photodiode21.

Therefore, as in the third embodiment, the infrared absorbing section 31e absorbs infrared light going toward the wiring layer 111 through thesemiconductor layer 101 before the infrared light is made incident onthe wiring layer 111. Thus, it is possible to prevent the occurrence ofcolor mixture, and therefore improve the color reproducibility of apicked-up image. Together with this, as in the third embodiment, thepresent embodiment can prevent the mixing of reflected light reflectedby the wiring 111 h in the wiring layer 111 in optical black (OB)pixels. Thus, noise components can be removed properly.

In particular, in the present embodiment, the infrared absorbing section31 e includes the part extending over the surface of the semiconductorlayer 101 from the part where the photodiode 21 is provided, so as tocover the gate electrode 22G of the transfer transistor 22. The presentembodiment can thus prevent the incidence of light on the wiring layer111 from a gap between the infrared absorbing section 31 e and the gateelectrode 22G of the transfer transistor 22, and hence produce theabove-described effect more desirably.

The present embodiment therefore makes it possible to easily improve theimage quality of a picked-up image in the “backside illumination type”solid-state imaging device.

6. Others

In carrying out the present technology, the present technology is notlimited to the foregoing embodiments, but various examples ofmodification can be adopted.

In the foregoing embodiments, description has been made of a case wherean infrared absorbing section for absorbing infrared rays is provided asa light absorbing section. However, the present technology is notlimited to a case of absorbing infrared rays. In addition to infraredrays, light having a longer wavelength than the light absorbed by thephotodiode 21 easily passes through the photodiode 21. Therefore a lightabsorbing section may be provided so as to absorb the transmitted lightof the longer wavelength.

In the foregoing embodiments, description has been made of a case wherefour kinds of transistors, that is, a transfer transistor, an amplifyingtransistor, a selecting transistor, and a reset transistor are providedas a pixel transistor. However, the present technology is not limited tothis. For example, the present technology may be applied to a case wherethree kinds of transistors, that is, a transfer transistor, anamplifying transistor, and a reset transistor are provided as a pixeltransistor.

In the foregoing embodiments, description has been made of a case whereone transfer transistor, one amplifying transistor, one selectingtransistor, and one reset transistor are provided for one photodiode.However, the present technology is not limited to this. For example, thepresent technology may be applied to a case where one amplifyingtransistor, one selecting transistor, and one reset transistor areprovided for a plurality of photodiodes.

In the foregoing embodiments, description has been made of a case wherethe present technology is applied to a camera. However, the presenttechnology is not limited to this. The present technology may be appliedto other electronic devices including a solid-state imaging device, suchas a scanner, a copying machine, and the like.

In addition, in the foregoing embodiments, description has been made ofa case where an infrared absorbing section is formed by using aninorganic material such as a metal, a semiconductor, or the like.However, the present technology is not limited to this. An infraredabsorbing section may be formed by using an organic compound.

In addition, the configurations of respective embodiments may becombined with each other as appropriate.

Incidentally, in the foregoing embodiments, the solid-state imagingdevice 1 corresponds to a solid-state imaging device according to anembodiment of the present disclosure. In addition, in the foregoingembodiments, the photodiode 21 corresponds to a photoelectric conversionsection according to an embodiment of the present disclosure. Inaddition, in the foregoing embodiments, the incident light H correspondsto incident light according to an embodiment of the present disclosure.In addition, in the foregoing embodiments, the semiconductor layer 101corresponds to a semiconductor layer according to an embodiment of thepresent disclosure. In addition, in the foregoing embodiments, theinfrared absorbing sections 31, 31 b, 31 c, and 31 e correspond to alight absorbing section according to an embodiment of the presentdisclosure. In addition, in the foregoing embodiments, the pixeltransistor Tr corresponds to a pixel transistor according to anembodiment of the present disclosure. In addition, in the foregoingembodiments, the wiring 111 h corresponds to wiring according to anembodiment of the present disclosure. In addition, in the foregoingembodiments, the wiring layer 111 corresponds to a wiring layeraccording to an embodiment of the present disclosure. In addition, inthe foregoing embodiments, the p-type semiconductor region 101 pacorresponds to a first impurity region according to an embodiment of thepresent disclosure. In addition, in the foregoing embodiments, then-type charge accumulating regions 101 na and 101 nb correspond to asecond impurity region according to an embodiment of the presentdisclosure. In addition, in the foregoing embodiments, the p-typesemiconductor region 101 pc corresponds to a third impurity regionaccording to an embodiment of the present disclosure. In addition, inthe foregoing embodiments, the insulating film 20 z corresponds to aninsulating film according to an embodiment of the present disclosure. Inaddition, in the foregoing embodiments, the polysilicon layer 300corresponds to a semiconductor film according to an embodiment of thepresent disclosure. In addition, in the foregoing embodiments, theP-type sections 300Pc and 300Pe correspond to a first semiconductorsection according to an embodiment of the present disclosure. Inaddition, in the foregoing embodiments, the N-type sections 300Nc and300Ne correspond to a second semiconductor section according to anembodiment of the present disclosure. In addition, in the foregoingembodiments, the floating diffusion FD corresponds to a floatingdiffusion according to an embodiment of the present disclosure. Inaddition, in the foregoing embodiments, the transfer transistor 22corresponds to a transfer transistor according to an embodiment of thepresent disclosure. In addition, in the foregoing embodiments, thecamera 40 corresponds to an electronic device according to an embodimentof the present disclosure.

The present disclosure contains subject matter related to that disclosedin Japanese Priority Patent Application JP 2010-225088 filed in theJapan Patent Office on Oct. 4, 2010, the entire content of which ishereby incorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alternations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalent thereof.

What is claimed is:
 1. A solid-state imaging device comprising: asemiconductor layer including a photoelectric conversion sectionconfigured to receive incident light and generate a signal charge; and alight absorbing section configured to absorb transmitted lighttransmitted by said photoelectric conversion section and having a longerwavelength than light absorbed by said photoelectric conversion section,the transmitted light being included in said incident light, the lightabsorbing section being disposed on a side of another surface of thesemiconductor layer on an opposite side from one surface of thesemiconductor layer, said incident light being made incident on the onesurface of the semiconductor layer.
 2. The solid-state imaging deviceaccording to claim 1, further comprising: a pixel transistor configuredto output the signal charge generated in said photoelectric conversionsection as an electric signal, the pixel transistor being disposed onsaid other surface of said semiconductor layer; and a wiring layercovering said pixel transistor on said other surface of saidsemiconductor layer and including wiring electrically connected to saidpixel transistor, wherein said light absorbing section is disposed so asto be interposed between a part including said photoelectric conversionsection in said semiconductor layer and said wiring layer.
 3. Thesolid-state imaging device according to claim 2, wherein: saidphotoelectric conversion section is formed so as to receive light of avisible light component in said incident light, and generate said signalcharge, and said light absorbing section is formed so as to absorbinfrared light of the transmitted light transmitted by saidphotoelectric conversion section.
 4. The solid-state imaging deviceaccording to claim 3, wherein said light absorbing section includes aSchottky junction that absorbs said infrared light by the Schottkyjunction.
 5. The solid-state imaging device according to claim 4,wherein said Schottky junction of said light absorbing section is formedby joining one of a metallic layer and a metallic silicide layer withsaid semiconductor layer.
 6. The solid-state imaging device according toclaim 5, wherein: said photoelectric conversion section includes (a) afirst impurity region of a first conductivity type, (b) a secondimpurity region of a second conductivity type different from said firstconductivity type, and (c) a third impurity region of the firstconductivity type; said first impurity region, said second impurityregion, and said third impurity region are sequentially formed from aside of said one surface to the side of said other surface in saidsemiconductor layer; and said Schottky junction of said light absorbingsection is formed by joining one of said metallic layer and saidmetallic silicide layer with said third impurity region.
 7. Thesolid-state imaging device according to claim 4, further comprising aninsulating film disposed on said other surface of said semiconductorlayer so as to be interposed between said semiconductor layer and saidlight absorbing section, wherein: said light absorbing section includesa semiconductor film disposed such that said insulating film isinterposed between said other surface of said semiconductor layer andthe semiconductor film, and said Schottky junction of said lightabsorbing section is formed by joining one of a metallic layer and ametallic silicide layer with said semiconductor film.
 8. The solid-stateimaging device according to claim 3, wherein said light absorbingsection includes a PN junction, and absorbs said infrared light by thePN junction.
 9. The solid-state imaging device according to claim 8,further comprising an insulating film disposed on said other surface ofsaid semiconductor layer so as to be interposed between saidsemiconductor layer and said light absorbing section, wherein: saidlight absorbing section includes (a) a first semiconductor section of afirst conductivity type, the first semiconductor section being disposedsuch that said insulating film is interposed between said other surfaceof said semiconductor layer and the first semiconductor section, and (b)a second semiconductor section of a second conductivity type opposite tothe conductivity type of said first semiconductor section, the secondsemiconductor section being disposed such that said insulating film andsaid first semiconductor section are interposed between said othersurface of said semiconductor layer and the second semiconductorsection; and said PN junction of said light absorbing section is formedby joining said first semiconductor section and said secondsemiconductor section with each other.
 10. The solid-state imagingdevice according to claim 9, wherein: said light absorbing sectionreceives said infrared light and generates a signal charge, and saidpixel transistor is disposed so as to further output the signal chargegenerated in said light absorbing section as an electric signal.
 11. Thesolid-state imaging device according to claim 9, wherein: said pixeltransistor includes a transfer transistor for transferring the signalcharge generated in said photoelectric conversion section to a floatingdiffusion, and said light absorbing section includes a part extending soas to cover a gate electrode of said transfer transistor from the partincluding said photoelectric conversion section at said other surface ofsaid semiconductor layer.
 12. A solid-state imaging device manufacturingmethod comprising: forming a semiconductor layer including aphotoelectric conversion section receiving incident light and generatinga signal charge; and forming a light absorbing section for absorbingtransmitted light transmitted by said photoelectric conversion sectionand having a longer wavelength than light absorbed by said photoelectricconversion section, the transmitted light being included in saidincident light, the light absorbing section being disposed on a side ofanother surface of the semiconductor layer on an opposite side from onesurface of the semiconductor layer, said incident light being madeincident on the one surface of the semiconductor layer.
 13. Anelectronic device comprising: a semiconductor layer including aphotoelectric conversion section configured to receive incident lightand generate a signal charge; and a light absorbing section configuredto absorb transmitted light transmitted by said photoelectric conversionsection and having a longer wavelength than light absorbed by saidphotoelectric conversion section, the transmitted light being includedin said incident light, the light absorbing section being disposed on aside of another surface of the semiconductor layer on an opposite sidefrom one surface of the semiconductor layer, said incident light beingmade incident on the one surface of the semiconductor layer.